sockets - Java TCP Client-send blocked? -

i writing java tcp client talks c server. have alternate sends , receives between two. here code.

1. the server sends length of binary msg(len) client(java)
2. client sends "ok" string
3. server sends binary , client allocates byte array of 'len' bytes recieve it.
4. it again sends "ok".

step 1. works. "len" value. client gets "send blocked" , server waits receive data.

can take look.

in try block have defined:

            socket echosocket = new socket("192.168.178.20",2400);             outputstream os = echosocket.getoutputstream();                    inputstream ins = echosocket.getinputstream();             bufferedreader br = new bufferedreader(new inputstreamreader(ins));              string frompu = null;               if( (frompu = br.readline()) !=  null){             system.out.println("pu returns  as="+frompu);                len = integer.parseint(frompu.trim());             system.out.println("value of len pu="+len);              byte[] str = "ok\n".getbytes();             os.write(str, 0, str.length);             os.flush();              byte[] buffer = new byte[len];             int bytes;             stringbuilder curmsg = new stringbuilder();             bytes =ins.read(buffer);             system.out.println("bytes="+bytes);              curmsg.append(new string(buffer, 0, bytes));                         system.out.println("ciphertext="+curmsg);                      os.write(str, 0, str.length);             os.flush();             } 

updated:

here code. @ moment, there no recv or send blocking on either sides. however, both buffered reader , datainput stream reader, unable send ok msg. @ server end, large number of bytes instead of 2 bytes ok.

            socket echosocket = new socket("192.168.178.20",2400);             outputstream os = echosocket.getoutputstream();                inputstream ins = echosocket.getinputstream();             bufferedreader br = new bufferedreader(new inputstreamreader(ins));             datainputstream dis = new datainputstream(ins);             dataoutputstream dos = new dataoutputstream(os);             if( (frompu = dis.readline()) !=  null){             //if( (frompu = br.readline()) !=  null){             system.out.println("pu server returns length as="+frompu);                   len = integer.parseint(frompu.trim());             byte[] str = "ok".getbytes();             system.out.println("str.length="+str.length);             dos.writeint(str.length);             if (str.length > 0) {                     dos.write(str, 0, str.length);                  system.out.println("sent ok");             }             byte[] buffer = new byte[len];             int bytes;             stringbuilder curmsg = new stringbuilder();             bytes =ins.read(buffer);             system.out.println("bytes="+bytes);                  curmsg.append(new string(buffer, 0, bytes));                             system.out.println("binarytext="+curmsg);               dos.writeint(str.length);             if (str.length > 0) {                     dos.write(str, 0, str.length);                  system.out.println("sent ok");             } 

using bufferedreader around stream , trying read binary data stream bad idea. wouldn't surprised if server has actually sent data in 1 go, , bufferedreader has read binary data line it's returned.

are in control of protocol? if so, suggest change send length of data binary (e.g. fixed 4 bytes) don't need work out how switch between text , binary (which pain).

if can't that, you'll need read byte @ time start until see byte representing \n, convert you've read text, parse it, , read rest chunk. that's inefficient (reading byte @ time instead of reading buffer @ time) i'd imagine amount of data being read @ point pretty small.